This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

This frame from an animation from NASA's Mars rover Curiosity shows the rover drilling into rock target 'Cumberland.' The drilling was performed during the 279th Martian day, or sol, of the Curiosity's work on Mars (May 19, 2013).

This image from the Mars Hand Lens Imager on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). The tool is a motorized, wire-bristle brush on the turret at the end of the rover's arm.

The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).

This Picasso-like self portrait of NASA's Curiosity rover was taken by its Navigation cameras, located on the now-upright mast. The camera snapped pictures 360-degrees around the rover, while pointing down at the rover deck, up and straight ahead.

As of June 2012, the target landing area for NASA's Mars Science Laboratory mission is the ellipse marked on this image of Gale Crater. The ellipse is about 12 miles long and 4 miles wide (20 kilometers by 7 kilometers).

This map shows the route driven by NASA's Mars rover Curiosity through the 43rd Martian day, or sol, of the rover's mission on Mars (Sept. 19, 2012). The route starts where the rover touched down, a site subsequently named Bradbury Landing.

This image from NASA's Mars Reconnaissance Orbiter shows wind-caused changes in the parachute of NASA's Mars Science Laboratory spacecraft as the chute lay on the Martian ground during months after its use in safe landing of the Curiosity rover.

This image from NASA's Curiosity shows a scoop full of sand and dust lifted by the rover's first use of the scoop on its robotic arm. In the foreground, near bottom of this image, the bright object visible on the ground might be a piece of rover hardware.

This evenly layered rock photographed by the Mast Camera (Mastcam) on NASA's Curiosity Mars Rover on Aug. 7, 2014, shows a pattern typical of a lake-floor sedimentary deposit not far from where flowing water entered a lake.

This is one of the first images taken by NASA's Curiosity rover, which landed on Mars the evening of Aug. 5 PDT (morning of Aug. 6 EDT). The clear dust cover that protected the camera during landing has been sprung open.

NASA's Curiosity rover found evidence for an ancient, flowing stream on Mars at a few sites, including the rock outcrop pictured here, which the science team has named 'Hottah' after Hottah Lake in Canada's Northwest Territories.

This photograph of the NASA Mars Science Laboratory rover, Curiosity, was taken during mobility testing on June 3, 2011. The location is inside the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

This southeastward-looking vista from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover shows the 'Pahrump Hills' outcrop and surrounding terrain seen from a position about 70 feet (20 meters) northwest of the outcrop.

The sinuous rock feature in the lower center of this mosaic of images recorded by the NASA Mars rover Curiosity is called 'Snake River.' Curiosity gets a closer look at Snake River for before proceeding to other nearby rocks.

This image, taken on Aug. 4, 2014, from the Navigation Camera on NASA's Curiosity Mars rover shows wheel tracks printed by the rover as it drove on the sandy floor of a lowland called 'Hidden Valley' on the route toward Mount Sharp.

The percussion drill in the turret of tools at the end of the robotic arm of NASA's Mars rover Curiosity has been positioned in contact with the rock surface in this image from the rover's front Hazard-Avoidance Camera (Hazcam).

This is a view of the third (left) and fourth (right) trenches made by the 1.6-inch-wide (4-centimeter-wide) scoop on NASA's Mars rover Curiosity in October 2012 and shows some of the details regarding the properties of the 'Rocknest' wind drift sand.

NASA's Mars rover Curiosity cut a wheel scuff mark into a wind-formed ripple at the 'Rocknest' site to give researchers a better opportunity to examine the particle-size distribution of the material forming the ripple.